Fire retarding systems based upon the combination of halogen-containing materials with antimony compounds such as oxides or halides of antimony have heretofore been extensively utilized to impart resistance to flame and combustion in polymeric compositions and other materials. For example, U.S. Pat. No. 2,480,298 of Aug. 30, 1949, teaches the use of at least 6 percent by weight of a chlorinated hydrocarbon in combination with 20 to 35 percent by weight of antimony trioxide as a flame proofing agent or system for polyethylene compositions.
The need for obtaining more effective resistance to flame or fire in polymeric products and other materials, moreover, has prompted efforts to improve this basic system of combinations of halogenated materials and antimony compounds such as are disclosed in U.S. Pat. Nos. 3,582,518; 3,740,245; and 3,741,893. Other recent patents, including U.S. Pat. Nos. 3,340,226 and 3,705,128, have proposed the use of a variety of metal compositions, such for example, as tin and zinc compounds, as substitutes or supplements for antimony compounds in halogen-containing fire retarding systems as a means of enhancing resistance to flame and overcoming shortcomings of the basic system.